The human heart consists of four chambers: the right atrium for receiving blood from systemic circulation; the right ventricle for receiving blood from the right atrium and pumping it to the lungs; the left atrium for receiving oxygenated blood from the lungs; and the left ventricle for receiving oxygenated blood from the left atrium and pumping it to systemic circulation.
The human heart also consists of four valves: the tricuspid valve located between the right atrium and the right ventricle; the pulmonary valve located at the output of the right ventricle; the mitral valve located between the left atrium and the left ventricle; and the aortic valve located at the output of the left ventricle.
In some circumstances (e.g., a birth defect, disease, etc.) a natural heart valve may need to be replaced by a prosthetic heart valve. In this situation, sometimes referred to as “on pump” surgery, the patient must be placed on a heart-lung machine and the heart stopped while the defective heart valve is removed and the prosthetic heart valve installed through a major incision made in the wall of the heart. The prosthetic heart valve is typically sutured in place at the annulus, or seat, of the natural heart valve using a sewing cuff disposed about the circular periphery of the prosthetic heart valve.
While such surgery is typically successful, it is also highly traumatic to the body and the use of the heart-lung machine may raise issues of subtle mental impairment in the near term following surgery.
In view of the trauma associated with a major coronary wall incision and possible subtle mental impairment which may be associated with the use of a heart-lung machine, it has been proposed to effect valve replacement without placing the patient on a heart-lung machine and stopping the heart. See, for example, PCT Patent Application No. PCT/US00/02126, filed Jan. 27, 2000 by Gregory Lambrecht et al. for CARDIAC VALVE PROCEDURE METHODS AND DEVICES, published Aug. 3, 2000 as PCT Patent Publication No. WO 00/44313. This type of surgery is sometimes referred to as “off-pump”, or “beating heart”, surgery.
It has been recognized that if a heart valve is to be replaced with “off-pump”, “beating heart” surgery, the incisions made into the vascular system should be as small as possible. However, this can make it difficult to secure the prosthetic heart valve in place, since the prosthetic heart valve is typically sutured to the annulus, or seat, of the natural heart valve, and since suturing (including knot tying) can be difficult to effect through small incisions. This can be particularly true where the incisions may be made into the vascular system at a location remote from the valve seat, e.g., in the superior vena cava in the case of the tricuspid valve, or in the pulmonary artery in the case of the pulmonary valve, or the pulmonary veins in the case of the mitral valve, or the aorta in the case of the aortic valve.